Supercritical fluid extraction and solid-phase extraction of AC 263,222 and imazethapyr from three Texas soils

Supercritical fluid extraction (SFE) using CO2 and solid-phase extraction ( SPE) are two technologies recently discussed in the literature as alternati ves to Soxhlet and liquid/liquid extraction (LLE). This research compared S FE and SPE extraction efficiency of two imidazolinone herbicides, AC263,222 and imazethapyr, from three soils. Recovery of the herbicides using SFE-CO 2 with a 4.6:1 acetonitrile:acetic acid cosolvent was approximately 80% for Poth and Tremona soils and 60% when extracted from Ships soil with high cl ay content and high pH. SPE recovery of both herbicides averaged 78% and wa s not statistically different between soils. Combining SPE disks with a SPE cartridge cleanup procedure provided a faster filtration with cleaner filt rate compared with using SPE C-18 cartridges by themselves. Cleanup was nee ded after both SFE and SPE disk extraction due to interfering peaks in the chromagraphy.